Marriage has long been, and remains to this day, the only form of gender relationship recognized as socially legitimate. This monopoly has only recently been shaken and partially broken in more developed countries. For this reason, it is particularly interesting today to reflect on why, in earlier times, it seemed unavoidable that the relationship between a man and a woman required public legitimization, and especially which authorities claimed the right to legitimize a gender relationship as marriage, and had enough power to enforce recognition of that claim. These are the questions that lie at the heart of this book. Schröter's investigation explicitly differs from legal and, above all, ecclesiastical legal historical traditions, which have traditionally encompassed this topic, at least in Germany.